A NOVEL METHOD TO PROTECT PLANTS FROM FUNGAL INFECTION

Abstract: A method for protecting a crop against fungal diseases comprising applying to the crop or its locus a composition containing an effective amount of an aminobutyric acid or derivatives thereof.

Description: A NOVEL METHOD TO PROTECT PLANTS FROM FUNGAL INFECTION I NTRODUCT I ON The present invention concerns a novel method to protect plants from pathogenic attack. The present invention more particularly concerns a method of applying selected compounds and compositions to a crop and its locus to induce local and systemic resistance of the crop to fungal diseases, wherein such action is referred to in this application as "induced plant defence" (hereinafter IPD). BACKGROUND OF THE INVENTION IPD in a crop is manifested by various defense mechanisms including the accumulation in the crop of soluble proteins referred to as pa thogenes i s-rela ted (PR) proteins. Some PR proteins have been shown to be hydrolytic enzymes such as chitinases and B-l, 3 - gluconases, while others are shown to be peroxidases. Also accumulated are a group of these proteins having a molecular weight or about 10 to 20 kDaltons referred to as P14 proteins, which are without known biological function. All of these proteins are believed to participate in the defense system of a crop. Various i sonicot inoyl-pyridinyl-hydrazine-derivat ives and benzothiadiazole compounds have been described in the patent literature as immunizing healthy plants against fungal diseases (European Patent Applications 0 268 775, 0 288 976 and 0 313 512). The use of DL-β-amino- bu-tyric acid for the control of root rot of peas caused by Aphanomvces euteiches Drechs. has also been described (Papavizas, Plant Disease Reporter, Vol. 48, No. 7. pp. 537-541 (1964), Papavizas, Plant Disease Reporter, Vol. 51, No. 2, pp. 125-129 (1967). The use of DL-α-aminobutyr ic acid at 0.03 M was described for the control of apple scab caused by Ven tur i a inaeσual i s (Kuc et al., 1959, Phytopathology 49:313-315) The use of DL-α-aminobutyric acid and DL-β-aminobutyric acid was described as chemotherapeu I an t s against the fungi Col letot richum cucumeri um and Col letotrichum 1agenar ium on cucumber and Pliytophlhora infestans on tomato (Oort, A.J.P. and Van Andel, O.M. , 1960, Mededel, Landbouwhogeschoo1 Opzoekin s s t a. Staal Gent 25:981-992) Various derivatives of DL-β-aminobutyr ic acid and β-aminocrotonic acid have been described in the patent literature as - fungicides against Phvtophthora infestans in tomato and Plasmopara vi .icola in grapes (DE-PS 1120802) Recently, Cohen, Niderman, Mosinger and Fluhr (Plant Physiol . (1994 ) 104:58-66 reported that PR proteins are involved in IPD in tomatoes. OBJECTIVES OF THE INVENTION It is the objective of the present invention to provide a novel method to induce IPD. It is a further objective of the present invention to provide a novel method to induce IPD in selected crops. SUMMARY OF THE INVENTION We have found a novel method of protecting a crop against fungal diseases caused by fungi by applying to the crop or its locus a composition containing an effective amount of a compound of formula (I): Ri and R2 are independently hydrogen, Ci-β alkyl, phenyl, and phenyl C1-4 alkyl R3 is hydrogen; C1-23 alkyl; carboxy C1-4 alkyl; phenyl C1-.4 alkyl; wherein the phenyl moiety is unsubs t i tuted or monosubs t i tuted by halogen; or C2-23 a1koxy-carbony1 Cι-4alkyl ; R4 and R5 are independently hydrogen or Ci-β alkyl; RG and R7 are independently hydrogen; CI-B alkyl C2-8 alkanoyl; phenyl C1-4 alkyl wherein the phenyl moiety is unsubs t i tuted or monosubs t i tuted by halogen; C2-8 alkoxy-carbony1 ; CONRβ wherein Re is is hydrogen, Ci-β alkyl, phenyl C1-4 alkyl; phenyl C2-4 alkyloxycarbony1 ; X is O, S or N, and salts thereof; and the crop is selected from the group consisting of corn, cucumber, melon, broccoli, cauliflower, kohlrabi, potatoes, cabbage, sunflower, tobacco, grapes, cotton, maize, sorghum, pearl millet, rice, lettuce, hop, avocado, citrus, soybean, and onion. DETAILED DESCRIPTION OF THE INVENTION Alkyl as used herein refers to straight chains, branched and cyclic forms and preferably contain one to four carbon atoms. Ri and R2 are preferably independently hydrogen, methyl or phenyl, more preferably Ri is hydrogen or methyl and R2 is hydrogen. R3 is preferably hydrogen. R4 and R5 are preferably independently hydrogen or C1-3 alkyl, more preferably R 4 is hydrogen or methyl and R5 is hydrogen or C1-3 alkyl, more preferably R is hydrogen or methyl and R5 is hydrogen. Re and R7 are preferably independently hydrogen, C1-6 alkyl, benzyl optionally substituted by halogen, more preferably Re is hydrogen or methyl and R7 is hydrogen. X is preferably oxygen. Preferred compounds of the invention are the amino- butyric acids and the aminovaleric acids; and most preferred are the aminobutyric acids (Scheme I) and especially R - β - aminobutyric acid. Scheme I COOH α-Aminobutyric acid (referred to as "AABA" ) CUOH β-Aminobutyric acid (referred to as "BABA" ) -Aminobutyric acid (referred to as "GABA" ) Salt forms of the compound of formula (I) contemplated in this application include acid addition salts such as those obtained by the addition of HCι,CF3 CO2H, toluene sulfonic acid, methane sulfonic acid and (Cθ2H)2 wherein Y is the residue of the acid; alkali metal salts such as those obtained by treatment with NaOH, KOH or LiOH wherein M is an alkali metal such as Na, K or Li; and acid addi t ion/a ine salts such as those obtained by treatment with HCl and an amine such as diethy1 amine , propyl amine, benzyla ine. wherein R a and R b are substituents Preferred crops in which the method of the present invention is applicable are cucumbers, melon, broccoli, cauliflower, kohlrabi, potatoes, sunflower, tobacco, grapes, cotton, maize, sorghum, cabbage, pearl millet, rice, and hop. Most preferred are sunflower, grapes, cucumber, melon, broccoli, kohlrabi, cauliflower, potatoes, tobacco and maize. The method of the present invention is not obvious in view of the prior art cited - especially that in regards to tomatoes. The reason is that the reported mechanism of IPD in tomatoes is via the formation of PR proteins. It has been found (Y. Cohen, unpublished results) that the mechanism in other plants is different. Thus it was found that the mechanism in, for example cucumbers and melons is via the accumulation of callose and lignin in the infected cells with no PR proteins involved. In addition, in tobacco it has been verified [Y. Cohen, Physiological and Molecular Plant Pathology (1994) 4_4_: 273-288], that protection against fungal infections was not associated with either PR protein, callose, or lignin. Fu thermore, the present method was effective against fungi already resistant to the major commercial chemical fungicides. Finally the present method was found to be effective even when applied pos t-infec t iona1 ly, and therefore the method is a cura t ive IPD. Production methods The novel compounds encompassed by the present application are structurally related to known compounds and can be easily prepared by either derivatising the known compounds or by modifying the procedures for preparing the known compound, as required. These procedures will be apparent to those skilled in the art The following procedures are illustrative. wherein Ri and R4-7 are as previously defined and R3 represents hydrogen or Ci-β alkyl can be obtained from a compound of the formula (Ila). To prepare compounds of formula (la) where Re is H and R7 is as previously defined, the compound of formula (Ila) is reacted with NR7H2 , wherein R7 is as previously defined. Reactions of this type are described in the literature, e.g., by A. Zilkha and J. Rivlin, Joe 1957, 23, 94. To prepare compounds of formula (la) where Re and R7 are as previously defined but excluding hydrogen, the compound of formula (Ila) is reacted with NRβR7Li , wherein Re and R7 are as previously defined but excluding hydrogen. Reactions of this type are described in the literature, e.g. , by Davies et al., Tetrahedron: Asymmetry, Vol.2, No.3, pp. 183-186 (1991). Compounds of the formula (Ila) are either known or obtainable from known compounds according to standard procedures . As can be appreciated, in such cases where R 4 and R5 do not represent the same substituent, the carbon atom to which they attach is chiral. Procedures for preparing each enantiomer form are either specifically described in the literature, e.g. , in EP 0 144 980 or in Davies, supra, or can be prepared according to analogous procedures . The present method was found to be effective against a variety of diseases. Examples are late blight, downy mildew, blue mold, leaf spots, fusarium wilt, trunk rot, fruit brown rot, damping off, white rust, black shunk and phytophthora ' s root rots. The compounds of this invention will typically be applied to crops or their locus before or after the onset or after the initial signs of fungal attack and may be applied to the foliar surfaces of the crop. The amount of the active ingredient to be employed will be sufficient to induce the systemic resistance of the crop to control the fungi and will vary depending on such factors as the species of fungi to be controlled, the type of treatment (for example, spraying dusting, seed treatment, soil drench), the condition of the crop, and the particular active ingredient used. As an application to the crop or its locus, the compounds will be applied to the crops with a dosage rate of from 0.1 to 5 kg/ha, preferably from 0.2 to 2kg/ha. with application being repeated as necessary, t.ypically at intervals of every one to three weeks. Depending on circumstances, the compounds of this invention may be used in association with other pesticides, e.g., fungicides, insecticides, acaricides, herbicides, or plant growth regulating agents in order to enhance their activity or to widen their spectrum of activity. The compounds of this invention are conveniently employed as fungicidal compositions in association with agriculturally acceptable carriers or diluents. Such compositions also form part of the present invention. They may contain, aside from a compound of formula (I) as active agent, other active agents, such as fungicides. They may be employed in either solid or liquid application forms e.g. , in the form of a wettable powder, an emulsion concentrate, a water dispersible suspension concentrate ("flowable"), a dusting powder, a granulate, a delayed release form incor orating conventional carriers, diluents and/or adjuvants. Such compositions may be produced in conventional manner, e.g. by mixing the active ingredient with a carrier and other formulating ingredients. Particular formulations to be applied in spraying forms such as water dispersible concentrates or wettable powders may contain surfactant such as wetting and dispersing agents, e.g., the condensation product of formaldehyde with naphthalene sulphonate, an aIky1-ary1-sulphona Ie, a lignin sulphonate, a fatty alkyl sulphate an ethoxylated alkylphenol and an ethoxylated fatty a1coho1. In general, the formulations include from 0.01 to 90% by weight of active agent, said active agent consisting either of al least one compound of formula (1) or ■mixture thereof with other active agents, such as fungicides. Concentrate forms of compositions generally contain between about 2 and 80%, preferably between about 5 and 70% by weight of active agent. Application forms of formulation may, for example, contain from 0.01% to 20% by weight, preferably from 0.01% to 5% by weight, of active agent. Formulation Example I; Wettable powder 50 parts by weight of a compound of formula (I) are ground with 2 parts of lauryl sulphate, 3 parts sodium lignin the sulphonate and 45 parts of finely divided kaolininite until the mean particle size is below 5 microns. The resulting wettable powder so obtained is diluted with water before use to a concentration of between 0.01% to 5% active ingredient. The resulting spray liquor may be applied by foliar spray as well as by root drench application. Formulation Example II: emulsion concentrate 25 parts by weight of a compound of formula I, 65 parts of xylene, 10 parts of the mixed reaction product of an alklphenol with xyleneoxide and calc ium-dodey1-benzene sulphonate are thoroughly mixed until a homogeneous solution is obtained. The resulting emulsion concentrate is diluted with water before use. Formulation Example III: Granulate (for soil treatments) Onto 94.5 parts by weight of quartz sand in a tumbler mixer is sprayed 0.5 parts by weight of a binder (non-ionic tenside) and is thoroughly mixed. 5 parts by weight of compound of the formula (I) in powdered form are then added and thoroughly mixed to obtain a granulate formulation with a particle size in the range of from about 0.3 to about 0.7 mm. The granulate may be applied by incorporation into the soil adjacent the plants to be tested. Formulation Example IV: Seed or Tuber Dressing 25 parts by weight of compound of the formula (I), 15 parts of dialkylphenoxypoly (ethylenoxy) ethanol, 15 parts of fine silica,, 44 parts of fine kaolin, 0.5 parts of a colorant (e.g., crystal violet) and 0.5 parts of xantham gum are mixed and ground in a contraplex mill at approximately 10,000 rpm to an average particle size of below 20 microns. The resulting formulation is applied tυ the seeds or tubers as an aqueous suspension in an apparatus suitable for that purpose. Where the compound of the formula (I) is liquid, it is first absorbed on the carriers, if desired with the air of a small amount of a volatile solvent such as acetone. The resulting powder is first allowed to dry if a solvent is used, then the other ingredients are added and the rest of the procedure is carried out . Formulation Example V: Soil Drench Drip Irrigation 2 parts by weight of compound of the formula (I) are dissolved in 1,000 parts of water. The resulting formulation is applied to plants by drip irrigation . As previously mentioned, the compounds of formula (I) are effective in activating or enhancing a crop's defense system against fungal diseases caused by fungi. Such activity can be demonstrated in using the general procedures of the following tests: Tes t A: IPD in potato plants against Phv toph thora infestans . Potato plants (cultivar Bintje) are grown from tubers in pots filled with sandy loam, peat and perlite mixed in equal volumes, in the greenhouse (20-22°C). The plants are ready for testing when they have 6 or 7 compound leaves. Tests are carried out with the met alaxy1-res i s tant isolated MR1 of Phvtophthora infestans. as well as the MS2, MS3, MR2 and MR3 isolates (Kadish and Cohen, Phytopathology, 78:912-9155 (1988). The fungus is grown on potato tuber slices at 15°C in the dark. Fresh sporangia are harvested at 6 days after inoculating the slices into double distilled water (4°C) and their concentration adjusted to 10,000 sporangia/ml before used for challenge inoculations. The compounds of this application are dissolved in water and sprayed on either the lower or upper leaf surfaces of the potato plants with a fine atomizer (about 10 ml per plant). The plants are left on the bench until the droplets dry and then are placed in a growth cabinet calibrated to 20°C and 14 hours of light per 10 day. Challenge inoculation with P. infesta s is carried out at time intervals ranging from 30 minutes to 12 days after treatment with the compounds, by spraying a sporangial suspension on the upper leaf surfaces (about 15 ml per plant). In one experiment, inoculum droplets (10 containing about 100 sporangia) are placed on the leaf surfaces, two droplets per leaflet, one on each side of the main vein. In another experiment the compounds are applied curatively, 24 hours after inoculation with P. infestans. Inoculated plants are kept at 100% RH in the dark for 24 hours at 20 18°C and then returned to a growth cabinet maintained at 20° C with 12 hours light per day. Disease severity is monitored 4-8 days after inoculation by visually estimating the proportion or a leaf area covered by blight lesions. Test B: IPD in tobacco plants against Peronospora tabacina . Tobacco plants (cultivars Ky-14 or Ky-16) are grown from seed in pots in the greenhouse. When reaching the 10-leaf stage or older the compounds of this application are injected into the stem of the plant. At 1-3 days before injection or at 1-10 days after injection plants are challenge-inoculated with conidia of the fungus Peronospora tabacina Adam which causes the blue mold disease. Conidia are harvested from previously infected tobacco plants. Inoculation is done with 10,000-100,000 conidia/ml, with approximately 50ml per plant. The procedure described above for inoculation, maintaining and scoring the disease are also applicable here. While the invention will now be described in connection with certain preferred embodiments in the following examples, it will be understood that it is not intended to limit the invention to these particular embodiments. On the contrary it is intended to cover all alternatives, modifications and equivalents as may be included within the scope of the invention as defined by the appended claims. Thus, the following examples, which include preferred embodiments, will serve to illustrate the practice of this invention, it being understood that the particulars shown are by way of example and for purposes of illustrative discussion of preferred embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of procedures, as well as of the principles and conceptual aspects of the invention. EXAMPLES EXAMPLE 1 : N-(2-hydroxyethyl )-aminobutyric acid A solution of 86g of crotonic acid (1 mole) and ethanol- amine (1 mole) in pyridine (200ml) is refluxed for 2-3 hours and subsequently cooled. The resulting product is filtered and recrys tal 1 i zed to yield the title compound having m.p. 178-180° C (compoundl.1 , Table 1). Following analogous procedure, the compounds 1.2-1.7, 1.10, 1.11, and 1.13-1.15 set forth in Table 1 are obt ained. EXAMPLE 2: 3-aminohexanoic acid A mixture of 2 hexenoic acid (7.0g, 0.06 mol) and concentrated aqueous ammonium hydroxide (70ml) is heated for 24 hours in an autoclave at 150°C. The cooled mixture is treated with carbon black and filtered. After evaporation of the solvent the crude product is recrys ta11 i zed from ethanol to give the title compound m.p. 203°C (compound 1.21, Table 1). Following an analogous procedure, the compounds 1.8, 1.9, 1.12 and 1.18-1.20 of Table 1 are obtained. EXAMPLE 3 : N-benzoy1-3-aminobut yr i c acid To a cooled solution of 3 - aminobutyric acid (13g) in 2M NaOH (130ml) is added benzoyl chloride (19.7g) over the course of two hours. The mixture is allowed to warm to room temperature. Washing with dielhyl ether, acidify¬ ing of the aqueous phase with 20% HCl, extraction with diethyl ether, drying over MgSθ4, evaporation of the solvent and reerys t a11 i za t ion in ether/hexane gives the title compound m.p. 150-152°C (compound 1.16, Table 1). Following an analogous procedure, compound 1.17 of Table 1 is obtained. TABLE 1 COMPOUNDS PREPARED OF THE FORMULA: 1.1 H CH 3 H hydroxye thyl 178-180 1.2 H CH 3 H i sopropy 1 167-169 1.3 H CH 3 H benzy1 178-180 1.4 H CH 3 H eyelohexy1 161-163 1.5 H CH 3 H n-hexy1 151-153 1.6 H CH 3 H p-chlorobenzy1 152-154 1.7 H CH 3 H benzyl 180-182 1.8 H ethyl H H 128-130 1.9 H CH 3 CH 3 H 216 1.10 CH 3 H H benzy 1 148 1.11 H CH 3 H pheny 1-e thyl 164 1.20 H pheny1 H H 220-221 1.13 H CH 3 H n-oc ty1 150 1.14 H CH 3 H n-decy1 148 1.15 H ethyl H benzy1 157-160 1.16 H CH 3 H benzoyl 150-152 1 ' - 1 H CH 3 H benzyloxyearbony 1128-130 1.18 H ethyl H H 178-180 1.19 H CH 3 H H 209-210 1.20 H CH 3 H CH 3 86-87 1.21 H propy1 H H 203 * (R) - enant iomer **monohydrate EXAMPLE 4 : N-benzyloxycarbony1 - 3 - aminobutyric acid ( -chloropheny1 )-1- ethylamide Z-protected β - aminobutyric acid (0.02ml), (4-chloropheny1 )-l- ethylamine and 1.1 equivalents of DCC (dieye1ohexy1 carbonimide) are stirred in ethyl acetate at room temperature for 16 hours. The precipitate is filtered, the filtrate evaporated and chroma tographed on silica gel (hexane /ethyl acetate 1:1) to give the title compound as a mixture of dias t ereomers m.p. 168-178oC. EXAMPLE 5 : β-aminobutyr i c acid hydroch 1oride 5.15 g β-aminobutyric acid (50 mol) are dissolved in 650ml methanol. After addition of 5.5ml concentrated HCl the solution is evaporated. The residue is triturated in diethyl ether, decanted and dried. A colorless oil is isolated. Microanalysi s : C.34.4; H, 7.2; N, 10.0; Cl, 25.4. EXAMPLE 6: β-aminobutyr c acid sodium salt 2.06g β-aminobutyric acid (20mol) are dissolved in 100ml of a mixture of water : me thanol (1:1). One equivalent NaOH in 10 ml water is added. The solution is evaporated and the resulting amorphous solid is dried. Microanalys i s : C, 37.4; H, 6.7; N, 10.9. EXAMPLE 7 : β-aminobut yr i c aci i e thy1 ammonium chloride 1.4 g β-aminobutyric acid (10 mol) are dissolved in 100 ml of methanol. Die thy 1 amine (0.9 g, 12.3 mol) is added and the residue is evaporated. The oily residue is washed with ether, decanted and dried to afford an amorphous material. H-NMR (CD 3 OD,200MHz) 1.29 (m, 9H, 3 CH 3 ; 2.25-2.45 ( , 2H, CH 2 ) ; 3.14 (p, 4H. CH 2 CH 3 ) ; 3.34-3.58 (m, 1H.CH) EXAMPLE 8: Protection of tomato plants against fusar iurn wi 1 t Tomato plants were grown in sterile soil in the greenhouse. When they reached the 4-leaf stage they were treated with compound of the formula (1) solution by a soil drench. Four days later the plants were uprooted, washed with water and their root system immersed for two minutes in conidial suspension (IO 7 conidia/ml) of the fungus Fusar ium oxysporum f.sp. 1ycoper s ici ■ Plants were then transplanted (without washing) in pots filled with sterile soil.Twelve days later all challenged - control plants wilted of the disease whereas none of the challenged treated plants wilted. Growth of the latter plants was similar to that of control, uncha1 lenged-uninocul a ted plants. Results are shown in Table 2. EXAMPLE 9: Following the method of Example 8, a similar experiment was run using lower concentration of BABA. The results are shown in Table 3. TABLE 2 Protection of tomato plants (cv. Rehovot - 13) against fusarium wilt caused by Fusarium oxysporum f.sp. lycopersici by aminobutyric acids (soil drench) Compound P cent of plants Healthy Wi 1 ted None 0 100 AABA 34 66 BABA 100 0 GABA 7 93 Plants were soil-drenched with 2000 ppm of the compound and inoculated 4 days later; rating was taken 12 days after inoculation. TABLE 3 Protection of tomato plants (cv. Rehovot - 13) against fusarium will caused by Fusarium oxysporum f.sp. lycopersici by lower concentrations of BABA (soil drench) Concentration (ppm) Percent Wilted Plants 0 100 250 53 500 43 1000 0 EXAMPLE 1 0 : Following the above described methods, the effect of aminobutyric acids on downy mildew in sunflower were studied. The results appear in Table 4, which shows the marked activity of "BABA" in percent protection. EXAMPLE 11; Following the above described methods, the effect of aminobutyric acids on Plasimopara viticola in grape plants were studied. The results which appear in Table 5, show the good protection given by "BABA". EXAMPLE 12: Following the above described methods, the effect of aminobutyric acids on downey mildew in cucumber and melon plants were studied. The results, which appear in Table 6, show the good protection given by "BABA". EXAMPLES 13 - 15: Following the above described methods, the effect of R-BABA and S-BABA against P. parasi tica and A. bassicola n broccoli, Kohlrabi, and cauliflower were studied; and the results, which appear in Tables 7 - 9, respectively, show the good protection given by R-BABA. TABLE 4 ; The effect of aminobutyric acids on systemic downey mildew of sunflowers (cv. D.I. -3) caused by PI asmopara halstedii . Compound Method of Cone . Percent Protection Appl ica t ion mg / 1 AABA spray . 2000 10 BABA spray 2000 100 GABA spray 2000 0 mg /P1 an t AABA soil drench 5 0 BABA soil drench 5 100 GABA soil drench 5 0 AABA root upt ake 2 0 BABA root upt ake 2 100 GABA root uptake 2 0 In all experiments inoculation with the fungus was done either 1 day before treatment (curative) or 2 days after treatment . TABLE 5 : The effect of aminobutyric acids on downy mildew caused by Plasmopara viticola in grape plants (vc. Sauvignon blanc or Cabarnet sauvignon) Cone . Ap l ica t ion 1 %prol ectioni with ppm • mo e AABA BABA GABA lOmg per plant soil drench 0 60 0 100 spraying} 0 30 0 200 intact } 0 60 0 500 plants } 15 90 5 1000 in pot s } 20 95 5 10 0 90 0 50 floating } 5 95 0 100 leaf discs } 1° 100 5 Disease rating was taken 9 days after inoculation. BABA has also curative effect as follows: When applied to inoculated leaf discs at 0, 1, 2 and 3 days after inoculation percent protection was 100, 86, 50 and 30 ftercent , respectively. TABLE 6 : The effect of aminobutyric acids on downy mildew caused by Pseudoperonospora cubens i s in cucumber and melon plants (foliar spray) or leaf iscs (floating) Percent protection by Plant & Cone whole lants cu1 t i var ppm AABA BABA GABA cucumber 250 0 0 0 (Dlila) 500 0 38 0 1000 0 65 0 2000 5 87 0 me1on 250 0 30 0 (Galia) 500 0 38 0 1000 0 86 0 2000 0 92 0 leaf discs cucumber 6 0 94 0 (Dlila) 12 0 97 0 25 0 100 20 50 0 100 60 melon 6 0 19 0 (.^.nanas ) 12 0 25 0 25 0 70 0 50 37 85 30 Disease rating was taken 7 days after inoculation, TABLE 7: (Broccoli ) Protection of Broccoli (cv. Shugon) against Peronospora paras i t ica and Alternaria brassicicola with amino butyric acids applied as a foliar spray. Compound Cone. ppm percent protection P. parasi tica A. brassicicola {125 33 0 .{250 50 20 R-BABA {500 95 60 {1000 100 85 {2000 100 90 S-BABA {500 0 tnot tes ted} {1000 0 } {2000 0 } TABLE 8: (Kohlrabi ) Protection of Kohlrabi (cv. White Wien) against Peronospora parasitica and Alternaria brassicicola with amino butyric acids applied as a foliar spray. Compound Cone. ppm percent protection P.parasi tica A. brassicicola {125 33 0 {250 50 20 R-BABA {500 95 60 {1000 100 85 {2000 100 90 S-BABA {500 0 not tested} {1000 0 } {2000 0 } TABLE 9: (Cauliflower) Protection of Cauliflower (cv. Nurit) against Peronospora parasi t ica and Alternaria brassicicola with amino butyric acid applied as a foliar spray. Compound Cone . pm percent protection P.parasi tica A. brassicicola {125 33 0 {250 50 20 R-BABA {500 95 60 {1000 100 85 {2000 100 90 S-BABA {500 0 not tested} {1000 0 } {2000 0 } EXAMPLE 1 6 : Following the above described methods, the effect of a 25% formulated DL BABA in potatoes was studied. The results are shown in Table 10. EXAMPLE 17: Following the above described methods, the markedly good effect of DL - BABA against the control of late blight in potatoes (Bintje in growth chambers was studied. The results are shown in Table 11 EXAMPLE 18: Following the method of Example 16 but running field trials in both Alpha and Bintje cultivars, the results are shown in Table 12. EXAMPLES 19-20: Resistance to Peronospora tabacina induced in tobacco plants was studied as outlined by Y. Cohen (Physiological and Molecular Plant Pathology (1994) 44:273-88) where the active ingredients were applied as a stem injection. Results for the stem injection are shown in Table 13. EXAMPLE 21: Following the method of Examples 19-20, the effect of a soil drench with DL- BABA (3mg per plant) on blue mold development in tobacco cv. Ky 16 showed an 80 percent control of the disease some 20 days after challenge inocula t ions . TABLE 1 0 EFFECT OF 25% WP FORMULATED DL-BABA IN POTATOES ppm DL-BABA Percent Protection Control 31 0 62 7 125 67 250 67 500 81 1,000 91 2,000 97 TABLE 1 1 Effect of aminobutyric acids against late blight in potato crops in growth chamber Control 2 0 4 80 6 95 8 98 10 98 GABA 2 0 4 60 6 85 8 90 10 98 2 0 4 45 DL-AABA 6 70 8 80 10 98 DL-BABA 2 4 0 6 10 8 10 10 10 TABLE 1 2 i Percentage control of late blight epidemics induced by Phytopthora infestans (isolate MRl) in potato crops treated with BABA (25 WP) in three independent field experiment s . Experiment dose Interval between sprays, days and cul t ivar Kg a.i. 7 10 14 per ha AutMil 0 0 Alpha 0.2 - - 24.6 0.4 - - 52.6 0.8 - - 55.1 Winter 0 0 0 0 Bint j e 0.2 55.0 42.1 38.4 0.4 57.4 52.5 47.1 0.8 62.6 62.6 58.0 Spring 0 0 - - Alpha 0.57 38.0 - - 1.15 77.7 - - 2.30 75.0 - - Spring 0 0 - - Bintje 0.57 35.2 - - 1.15 64.5 - - 2.30 76.0 TABLE 1 3 : Resistance to Peronospora tabacina in tobacco plants by aminobutyric acids via stem injection Compound St em Inj ect ion Disease Severity (mean ± SD) Water 2.0 ± 0a DL- AABA 1.3 ± 0.2b DL-BABA 0.7 + 0.2c R-BABA 0.07 ± 0.09d GABA 2.0 ± 0a SA* 1.5 ± 0b INA b 0.5 ± 0c β Sodium salicylate b 2,6 dichloro-iso-nicotinic acid The letters refer to statistics EXAMPLE 22 : Sunflower plants were protected against downy mildew caused by PI asmopora halstedii by treating the seeds i t-h BABA. Thus, the seeds were soaked for 24 hours in solution containing lOmg BABA per ml, and then sown in pots in the greenhouse.Two weeks later the developed plants were inoculated with P 1 asmopora halstedii . The progress of the disease was assessed after seven more days with the following results: While the control had 100 percent of the plants remained infected; the treated plants had only a 2 percent rate of infection. EXAMPLE 23: Maize (Line 3376) seeds were allowed to sprout in water for 5 days. They were then dipped in a BABA solution for one day. The sprouted seeds were washed and placed in contact with Fusar iurn moni 1 i forme for one day and then planted in pots. After two weeks the progress of the disease was as follows: BABA (ppm) 0 1 25 250 5 00 2 . 000 Percent plants 70 80 40 0 0 infected. EXAMPLE : 24 The activity of DL-α-aminobutyric and DL-β-aminobutyric acids against late blight (Phyt opht ora infestans) on various potato cultivars in growth chambers was studied. Six week old plants in pots were sprayed with the compounds and inoculated two days later. Disease records taken 7 days post-inoculation are listed in Table 14. TABLE 14 Activity of DL-α-aminobutyr ic and DL-β-aminobutyric acids against late blight (Phy toph t ora infestans) on various potato cultivars in growth chambers. Compound % proleclion and cone . ppm Ni co 1 a Agr i a Cl [ aus 1 :er Spun t a DL-α 500 - - 92 - 1000 - - 97* - 2000 71 86 97* 65 DL-β 500 - - 33 - 1000 - - 73 - 2000 57 97 91 94 = Some phy to to ici t y .

Claims: WHAT IS CLAIMED IS: A method for protecting a crop against fungal diseases caused by fungi comprising applying to the crop or its locus a composition containing an effective amount of a compound of formula (I): wherein: (a) Ri and R2 arc independently hydrogen, Ci-β alkyl, phenyl, and phenyl C1-4 alkyl; (b) R3 is hydrogen; C1-23 alkyl; ca boxy-Ci -4 alkyl; phenyl C1-.4 alkyl; wherein the phenyl moiety is unsubs t i tuted or monosubs t i tuted by halogen; or C2-23 alkoxycarbony1 C1 _4 alkyl; (c) R4 and R5 are independently hydrogen or Cι_β alkyl; (d) Rε and R7 are independently hydrogen; Ci-β alkyl; C2-8 alkanoyl; phenyl Cl-4 alkyl wherein the phenyl moiety is unsubs t i tuted or monosubs t i tuted halogen; C2-8 alkoxycarbony1 ; C0NR8 wherein R8 is hydrogen Cl-8 alkyl, phenyl phenyl Cl-4 alkyl; phenyl C2-4 alkyloxycarbonyl ; (e) X is 0, S or N, and salts thereof; and the crop is selected from the group consisting of corn, cucumbers, melons, broccoli, cauliflower, kohlrabi, sunflower, potatoes, tobacco, grapes, cotton, cabbage, maize, sorghum, pearl millet, rice, lettuce, hop, avocado, citrus, soybean and onions in an amount sufficient to induce local and systemic resistance of the crop to control the fungal disease. 2. A method according to claim 1, wherein Ri and R2 are independently hydrogen, methyl or phenyl, R3 , is hydrogen, R and R5 are independently hydrogen or C1-3 alkyl. Re and Rv are independently hydrogen, Ci-β alkyl or benzyl optionally substituted by halogen and X is oxygen. 3. A method according to claim 2, wherein Ri is hydrogen or methyl, R2 is hydrogen, R4 is hydrogen or methyl, R5 is hydrogen, Re is hydrogen or methyl and R7 is hydrogen. 4. A method according to claim 1. wherein the compound of formula (I) is R β-aminobu t yr i c acid or β-aminovaler ic acid. 5. A method according to any of Claims 1 to 4 wherein the crop is selected from the group consisting of cucumbers, melon, broccoli, cauliflower, kohlrabi, potatoes, sunflower, tobacco, grapes, cotton, maize, sorghum, cabbage, pearl millet, rice and hop. 6. A method according to any of Claims 1 to 4 wherein the crop is selected from the group consisting of sunflower, grapes, cucumber, melon, broccoli, kohlrabi, cauliflower, potatoes, tobacco and maize. 7. A method according to any of Claims 1 to 6 wherein the compound is applied to the leaves or stems of the plant . 8. A method according to any of Claims 1 to 6 wherein the compound is applied to the roots of the plant. 9. A method according to any of Claims 1 to 6 wherein the compound is applied to the soil. 10. A method according to any of Claims 1 to 6 wherein the compound is applied to the seeds, tubers, or bulbs of the plant. 11. A method according to any of Claims 1 to 10 wherein the compound is applied pre-e ergence. 12. A method according to any of Claims 1 to 10 wherein the compound is applied pos t -emergence . 13. A method according to any of Claims 1 to 12 wherein the compound is applied to the crop at a dosage rate of from 0.1 to 5 kg/ha. 14. A method according to any of Claims 1 to 12 wherein the compound is applied to the crop a dosage rate of 0.2 to 2 kg/ha. A method for protecting tomatoes against Fusarium oxysporum of Sp. Lvconer s i ci comprising applying to the tomato plant or its locus an effective amount of the compound of formula I: whe r e i n : (a) Ri and R2 are independently hydrogen, Ci-β alkyl, phenyl, and phenyl C1-4 alkyl; (b) R3 is hydrogen; C1-23 alkyl; carboxy-Cι-4 alkyl; phenyl C1-4 alkyl; wherein the phenyl moiety is unsubs t i tuted or monosubs t i tuted by halogen; or C2-23 a1koxycarbony1 C1-4 al yl; (c) R4 and R5 are independe tly hydrogen or Ci-β alkyl; (d) Re and R7 are independently hydrogen; Ci-β alkyl; C2-8 alkanoyl; phenyl C1-4 alkyl wherein the phenyl moiety is unsubs t i tuted or monosubs t i tuted halogen; C2-8 a1koxycar ony1 ; CONRβ wherein Re is hydrogen, Ci-fl alkyl, phenyl C1-4 alkyl; phenyl C2-4 al yloxycarbony1 ; and (e) X is 0, S or N, and sails thereof. 16. A method according to claim 15, wherein Ri and R2 are independently hydrogen, methyl or phenyl, R3 is hydrogen, R4 and R5 are independently hydrogen or C1-3 alkyl, Re and R5 are independently hydrogen, Cl-6 alkyl or benzyl optionally substituted by halogen and X is oxygen. 17. A method according to claim 15, wherein Ri is hydrogen or methyl, R?_ is hydrogen, R 4 is hydrogen or methyl, R5 is hydrogen, Re is hydrogen or methyl and Rv is hydrogen. 18. A method according to Claim 15, wherein the compound of formula (I) is R-β-aminobutyr ic acid or β-aminova leric acid. 19. A method according to any of Claims 15 to 18 wherein the compound is applied to the leaves or stems of the plant . 20. A method according to any of Claims 15 to 18 wherein the compound is applied to the roots of the plant. 21. A method according to any of Claims 15 to 18 wherein the compound is applied to the soil. 22. A method according to any of Claims 15 to 18 wherein the compound is applied to the seeds, tubers, or bulbs of the plant. 23. A method according to any of Claims 15 to 21 wherein the compound is applied pos t-emergence . 24. A method for protecting potatoes against fungal diseases selected from the group consisting of late blight, early blight and leaf spots, applying to potato plants or its locus a composition containing an effective amount of DL-α-aminobutyric acid, D-cr- aminobutyric acid, L-aminobutyr ic acid, or mixtures thereof . 25. A method according to Claim 24 wherein the compound is applied to the leaves or steins of the plant. 26. A method according to Claim 24 wherein the compound is applied to the roots of the plant. 27. A method according to Claim 24 wherein the compound is applied to the soil. 28. A method according to Claim 24 wherein the compound is applied to the seeds, tubers, or bulbs of the plant .

Inventors: COHEN YIGAL, COHEN, YIGAL
Applicants: AGROGENE LTD, COHEN A DAVID, COHEN YIGAL, AGROGENE, LTD., COHEN, A., DAVID, COHEN, YIGAL
Application year: 1994
Main classification: A01N37
IPC codes: A01N37, A01N47, A01P13